Building the O2 Headphone Amp

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#22
RugbyPlayer said:
Thanks for that. i am hoping to DIY it. The thing i still cant seem to find is a schematic that tells me where everything needs to be put.

Do you know anything about this kit posted here? O2 Headphone Amplifier Full Kit
Click to expand...

The schematic is here: https://docs.google.com/file/d/0B52...mLWIwM2MtNDI4ZWU4YWRjY2Y4/edit?hl=en_US&pli=1 same deal, file->download to open or download a PDF. But like shadow419 says, the boards are silkscreened so all you really need is the BOM.

That amp kit is Head-N-HiFi, the second link I posted. All 4 of those outfits (last I checked anyway) offer the bare PC board, parts kits, and soldered-together finished units. You can choose if you want to DIY it or buy one assembled.
 
#23
RugbyPlayer said:
Thanks for that. i am hoping to DIY it. The thing i still cant seem to find is a schematic that tells me where everything needs to be put.

Do you know anything about this kit posted here? O2 Headphone Amplifier Full Kit
Click to expand...

I bought pcb, case and component pack from headnhifi, I already had a power supply and I didn't need the batteries. (Was fitting an ODAC in the case), very economical and good service, so I imagine the full kit will be very good.
 
#26
#27
Thanks John! That's a good guide but I'm still not feeling very confident about understanding what's going on in method 2, step 6 and 7. The pictures are very small and what's happening with the ground wire/wires? is a bit sketchy to me.

What would be really be awesome are some high res photos for method 2 of the soldered wires and cut traces on the O2 board together with a photo of the mounting on the ODAC board.
 
#28
Hi!
I've build my own O2. And I've some trouble...

o2-com10.jpg


The amp sound like "mono". It "sum" left channel with right channel, and the common part went "masked", silenced.
In a stereo song, like a "karaoke"...

If i feed it with "mono" music, nothing come out...

What's wrong???
What can I test?

(sorry for my poor english...)
 
#32
Since the AC supply is isolated there is not ground thorugh it.

The only ground connection will be made to the source, if the source is grounded.

Othewise, the entire system is floating.

For instance, you have the O2 powered by a wall plug AC transformer, and are using a cellphone as the audio surce. There is no ground connnection in this configuration and the entire system is floating.

If on the other hand,you have the source as a console receiver using the headphone output, it provides a ground connection by way of the shield on the interconnect cable.
 
#33
It shouldn't. I bought an O2 with a power socket on the back of the enclosure, vendor fitted one that was metal and connected the body of the AC plug to the chassis which created a mains hum. I switched it out for a plastic body insulated socket and the noise went away.
 
#34
One more question.

In all manuals we can see 2 methods to connect O2 and ODAC according to usage of 3.5 input socket: 1) to keep O2 input on it, 2) to change it to ODAC output.

However, ODAC has two outputs: four pins in the middle of PCB and 3.5 mm socket. Why nobody uses them both? Pins to connect ODAC with O2 and 3.5mm socket to get direct ODAC output. Does such setup affect the output quality with some negative influence of O2 input?
 
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#35
I've noticed that round area of the power plug has contact with the enclosure (it is not a ground pin because of AC).
Click to expand...
The outer ring of the pin is at same potential (in this case zero w.r.t. +/- supplies) and is connected to main power GND. So no fireworks even if it touches panel. You can expand the hole using some round file or drill it to enlarge a little.I've used sleeves made of LAN cable's outer plastic insulation & fitted it on the AC pin to avoid this issue.
And it is also recommended to connect a signal ground to the chassis too. Is it normal?
Click to expand...
Yes to reduce noise(i/p gnd is the only thing that should be connected to the main body/front panel) and that's why your AC pin should not touch the panel(in the first place itself)

Pls post all your O2 related queries on this official thread-
http://www.diyaudio.com/forums/head...ective2-o2-headphone-amp-diy-project-394.html
 
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#36
Thanks to the OP for this thread and the folks behind the amp. I have found my first DIY project. I know how to solder and have worked on small boards before (was repairing radio controlled electronics for 15 years) so I should be good.

I saw the link for the bare board, can I get the link for the enclosure, faceplate, and power supply? I think I missed those.

Thank you!
 
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